Table 2. Selection of main structural parameters involved in Steps 1.

	4-endo conformation					5-endo conformation
	Reactive	ICR	TS	ICP	Product	Reactive	ICR	TS	ICP	Product
Distances (angstroms)
C1-C2	1.546	1.536	1.529	1.722 a	1.795	1.543	1.535	1.528	1.704	2.711
C2-N	1.510	1.494	1.481	1.382	1.373	1.505	1.495	1.482	1.384	1.397
N-H8	1.045	1.051	1.207	2.709	-	1.040	1.052	1.202	2.696	-
C1-O1	1.243	1.241	1.235	1.222	1.219	1.243	1.241	1.236	1.223	1.168
C1-O2	1.258	1.267	1.281	1.231	1.218	1.258	1.267	1.280	1.233	1.168
O2-H8	1.808	2.329	2.287	1.825	-	1.847	2.186	2.284	1.786	-
O3-H8	-	1.670	1.278	0.978	-	-	1.668	1.285	0.980	-
Angles (degrees)
C2-C1-O2	115.8	119.2	120.3	112.2	109.4	115.6	119.6	120.6	113.5	92.1
O1-C1-O2	128.9	125.5	122.0	135.4	139.9	128.9	125.3	122.0	134.6	173.2
N-C2-H1	109.4	109.0	109.5	113.4	115.2	108.1	108.0	108.7	112.4	119.1
N-H8-O3	-	163.4	168.4	85.6	-	-	162.1	168.0	86.5	-
Dihedral (degrees)
H8-N-C1-O2	2.7	26.4	19.1	5.1	-	−8.7	23.9	12.4	8.7	-

^a Note that major changes are highlighted in bold.